Spotlight Search Not Working

My dad is getting frustrated with his iPhone 4S. He has 800 contacts (that's what real estate does to you), and he usually just uses Spotlight Search to find a certain contact. He doesn't enjoy searching in the Contacts app. Lately, Spotlight Search has stopped searching all at once. It only works when you open Settings > General > Spotlight Search. Before I restore, I wanted to ask whether any of you are experiencing the same issue.

As a side note, my dad has a 16GB iPhone 4S running iOS 5.0.1. It's not jailbroken either.

Try go to Settings>General>Spotlight and untick everything Reboot the phone try search something (nothing will appear) then reboot again (without backspacing words) turn on the settings again reboot again and it should work.

I'm sure he rebooted. Look guys, it's not that it takes long. If I go into Settings > General > Spotlight Search, and exit, Spotlight Search takes an instant to load possible contacts when searching. I have to open that every time if it doesn't show contacts, and then it works.

And why would we ask Siri, which requires an Internet connection, when we should be able to instantly search? In our area, it takes a while for Siri to respond. The fact that my dad doesn't use our WiFi doesn't help either.